I think Enterbrain license for using their tileset or tileset derived from their tileset requires to have license RPGMaker and only make games with RPGMaker. Enterbrain might have some tileset they sell for general purpose use but I am not sure. Just a note that I haven't read the Enterbrain license text but I am quite sure they do not just give away their tilesets.

Anyway you could check tilesets from here and choose licenses which suite you best...

For example here:

http://opengameart.org/content/mage-city-arcanos

That is licensed under CC0 which is public domain.

Since you wanted to make RPG for iPhone you should stick with CC0 licenses or OGA-BY since CC-BY and CC-BY-SA licenses forbids DRM and iPhone programs always have DRM. You can always contact the author here and ask if they would allow you to use their art on iPhone game even it is licensed under CC-BY or CC-BY-SA.

When you are using art always check the license you want to use unless you are familiar with that. You can view the license simply clicking the license icon next to art.

LPC Tileset is a great one. 

You should learn how to use search here :)

Any way  here is link where I simply searched LPC with licenses OGA-BY and CC0:

http://opengameart.org/art-search-advanced?keys=lpc&field_art_type_tid%5...

LPC stands for Liberated Pixel Cup. More information from here: http://lpc.opengameart.org/

You could leave art request here in OGA but before writing that to forum, please read this thread first:

http://opengameart.org/forumtopic/how-and-when-to-write-a-good-art-request

I am not sure. Some of those tiles are from REFMAP/First Seed Material but not all. REFMAP/FSM site has been down almost year, I think. REFMAP/FSM had license that you use their tileset freely but only distribute it with your game not the tileset itself. So anywhere you can find their tileset is breaking the license.

Plus since not all those tiles are from REFMAP/FSM I have no idea under what license they are.

So shortly say I would not use that tileset in my games.